SAN DIEGO — To playwright-librettist Joe Masteroff, life is more than a cabaret, ol' chum. Yet his best-known book, about the lost souls of the Kit Kat Klub, has served him in a perfectly marvelous, if unanticipated, way.

"The original production of 'Cabaret' was a big success, much to our surprise," recalls the writer, who won a Tony for his efforts. "In 1966, doing a production about abortions and Nazis--a production which ended unhappily for every character in the cast--people forget how revolutionary that was."

Revolutionary or not, there's no denying that Masteroff's book--as well as his earlier "She Loves Me"--has had staying power. "I've had 10 opening nights just on 'Cabaret' and 'She Loves Me,' in the West End of London and New York: 'Cabaret' has been done three times in each place, and 'She Loves Me' twice," says Masteroff over dinner in a restaurant near the Old Globe Theatre, where his latest work, "Paramour," premiered Saturday night. The new musical, created with composer Howard Marren and directed by Joseph Hardy, is based on the play "The Waltz of the Toreadors" by often-whimsical French playwright Jean Anouilh (1910-87).

"Who would ever have dreamt that this fashion for reviving shows would happen?" he says. "It didn't exist at the time that these shows were written. But I guess as there were fewer and fewer Broadway musicals, the need for revivals got greater."

Either that, or "Cabaret" and "She Loves Me" just have that certain elemental something that can withstand the changing tastes of generations of theatergoers.

And that, while no secret, is an ingredient that's as basic as it can be elusive. "The most important thing when you're doing a musical is having a good idea," Masteroff says. "The day you sit down to write 'Act 1, Scene 1,' the show is a good show or a bad show, depending on what your idea is."

In the case of "Paramour," Masteroff has liked Anouilh's idea--about the farcical entanglements of a philandering general, his invalid wife, his virginal love and others--since the 1950s, when "The Waltz of the Toreadors" was first produced.

Years, then decades passed, during which Masteroff tried and failed to acquire the rights to adapt the piece. But eventually, when the rights finally became available in the 1980s, Masteroff jumped at the opportunity.

Then he was able to turn his attention to the piece's artistic challenges, which were considerable. "My big question was whether musical audiences could adjust to the changes of style," Masteroff says. "This is a play that goes from Feydeau to Strindberg without taking a breath. I've always loved that. But I didn't know if audiences would."

What it had going for it, Masteroff figured, was an inherent musicality. "I loved the fact that in the play the wife is an opera singer, and the general had sort of forced her to give up her career when she married him," he says. "But as her revenge, she only sings to him, she never speaks."

That plot point made the translation from text to book and lyrics comparatively organic. "You can make anything into a musical, truth is," says Masteroff, who also wrote the lyrics. "But if it's an intrinsically musical idea, it works a lot better.

"A show that takes place in a carnival or a theater or somewhere with a musical background is a lot easier to do than a show that takes place in a shooting gallery," he says. "People can sing about anything, obviously, but somehow if the ambience is such that they should be singing, it makes it easier.

"One reason that so many musicals are costume musicals is that audiences are more willing to accept the singing in costume musicals. There are some very successful contemporary musicals, but they're very much the exception. Most musicals are of another period."

Another way of looking at it is that Masteroff went with, rather than against, the grain of the work he set out to adapt. "He preserved Anouilh's wit and style and infused it with his own sense of humor," says composer Marren, who has known Masteroff for 16 years and also wrote the 1986 musical "Georgia Avenue" with him. "And it's a page-turner; you're dying to know what's going to happen next. He's always a step ahead of you."

Nor does it hurt that Masteroff works quickly and provides what every composer wants: settable lyrics. "We added a title song last week and he did it in about an hour one morning," Marren says. "I put it on the piano and it just happened. It's that way with everything he gives me. They suggest tunes by themselves."

Masteroff, now a surprisingly young 78, may be so adept at what he does because he's loved music and the theater for as long as he can remember. Born and raised in Philadelphia, he grew up with parents who were fans of plays and opera and attended both regularly.

"In those days, the Metropolitan Opera went to Philadelphia every Tuesday night," he recalls. "And there was always music in the house, opera records."